> ... Deno is (and always will be) a single executable file. Like a web browser, it knows how to fetch external code. In Deno, a single file can define arbitrarily complex behavior without any other tooling. > ... > Also like browsers, code is executed in a secure sandbox by default. Scripts cannot access the hard drive, open network connections, or make any other potentially malicious actions without permission. The…
If you're building a real world application, especially a server application like in the example, you're probably going to want to listen on the network, do some db access and write logs.
For that you'd have to open up network and file access pretty much right off the bat. That combined with the 'download random code from any url and run it immediately', means it's going to be much less secure than the already not-that-secure NPM ecosystem.